复合式A/O工艺处理晚期垃圾渗滤液的脱氮特性

Characteristics of Nitrogen Removal from Aged Landfill Leachate by Hybrid A/O Process

针对A/O工艺处理晚期垃圾渗滤液的过程中因碳源不足而脱氮效果不佳的问题,在传统A/O工艺的曝气池中加入生物载体而构成复合式A/O工艺,通过创造缺氧微环境来实现同步硝化反硝化(SND),从而达到强化脱氮的目的。考察了温度、溶解氧、pH对亚硝酸盐积累的影响,以及SND对去除总氮的贡献率。结果表明,复合式A/O工艺对晚期垃圾渗滤液的处理效果良好,对氨氮的去除率>99%,出水氨氮<20 mg/L,达到了二级排放标准。当回流比为2时,对TN的平均去除率为72%。生物载体的加入,在曝气池内创造了缺氧微环境,为进行SND提供了有利条件,提高了对总氮的去除效果。亚硝化率稳定在95%以上,DO和温度对亚硝化率的影响很小,高pH值是实现亚硝酸盐积累的决定性因素。

In order to solve the problem of poor nitrogen removal efficiency due to insufficient car- bon source during treatment of aged landfill leachate by A/O process, a hybrid A/O process was estab- lished by adding biological carriers into the aeration tank of the conventional A/O process so as to achieve simultaneous nitrification and denitrification （SND） by creating anoxic micro-environment and reach the goal of enhanced nitrogen removal. The effects of temperature, dissolved oxygen （DO） and pH on nitrite accumulation, and the contribution of SND to total nitrogen removal were investigated. The results show that the removal effect of aged landfill leachate by hybrid A/O process is excellent, the removal rate of ammonia nitrogen is more than 99% , and the effluent ammonia nitrogen is less than 20 rag/L, which meets the national second class discharge standard. When the reflux ratio is 2, the average removal rate of TN is 72%. Adding biological carriers into the aeration tank provides favorable conditions for SND by creating anoxic micro-environment, so the removal efficiency of total nitrogen is enhanced. The nitrosati- on rate is stabilized at more than 95%, and the effects of DO and temperature on nitrosation rate are very small, so high pH is the decisive factor for nitrite accumulation.